1. Field of the Invention
The present invention relates to a method of reproducing a disk such as mini-disk (MD) or compact disk (CD) or the like, and more particularly to a method for reproducing desired programs using address information recorded in a TOC area of the disk.
2. Description of the Prior Art
The mini-disk eliminates deterioration of sound quality even after long use through digital recording of music just like a compact disk, but it is of smaller size than the compact disk and insures easy handling and improved durability through accommodation within a hard case. Moreover, the mini-disk has a recording time as long as that of the compact disk by digital recording of compressed music signals.
A system for playing a mini-disk intermittently reads data at high speed from the mini-disk, then writes data into a data memory and thereafter continuously reads such data from the data memory at normal speed. Even if the pickup jumps the track due to a shock during playback, and playback (reproduction) is discontinued or transiently interrupted, playback continues by returning the pickup to the initial position within a period when data still remains in the data memory. Therefore, such a mini-disk system is suitable for use in a car or for outdoor use, such as a portable mini-disk system.
In the case of a compact disk, TOC (table of contents) information is recorded in a read-in Q channel subcode. This TOC information includes playback start position information (playback start time) on the disk for each program (track number) and is used for searching, in the case of selecting and reproducing a desired program, the point where the absolute time recorded in the Q channel subcode of the program area matches the playback start time of the desired program, enabling playback of the desired program within a very short period by starting playback after searching for such a point.
In the case of a mini-disk, like a compact disk, position information consisting of the start address and end address for each program is recorded in the read-in TOC area for a reproduction only (read only) disk, or in the UTOC area (user TOC area) provided at the initial area of the program area for a disk (MD-MO mini disk magneto-optical) for both reproduction and recording (read-write). Accordingly, the desired program can be played within a short time by searching for the point where the address recorded in the subdata of the program area of the playback only disk or the address recorded in the pregroove of the reproduction and recording disk matches the start address of the desired program, and then starting playback after searching for such a point.
In the case of either a compact disk or mini-disk, until the time for starting playback, position information for all programs is read from the TOC area or UTOC area under the control of a system controller, the readout information is automatically stored in a work memory incorporated with the system controller, and the stored position information is held within the work memory until the disk is changed. For selection and playback of programs, the desired program is searched by making reference to the work memory.
However, in this case the position information about e.g., all 99 programs on a compact disk or all 255 programs on a mini-disk must actually be stored simultaneously in the work memory, and therefore a large memory area must be assigned for this purpose, resulting in the problem that acquisition of memory capacity required for other tasks is restricted and/or provision of sufficient memory capacity increases cost and prevents reduction in memory size.
For example, storing of all the start addresses and end addresses of the programs recorded on a mini-disk requires 1530 bytes, and requires 1785 bytes total including also track mode information.